Display screen or portion thereof including a graphical user interface



FIG. 1 is a front view of a first embodiment of the display screen or portion thereof including a graphical user interface according to our new design.

FIG. 2 is a front view of a second embodiment of the display screen or portion thereof including a graphical user interface according to our new design.

FIG. 3 shows the graphical user interface of the first embodiment; and,

FIG. 4 shows the graphical user interface of the second embodiment.

The broken lines showing a display screen or portion thereof, and elements of the graphical user interface illustrate portions of the article, and form no part of the claimed design. 

CLAIM The ornamental design for a display screen or portion thereof including a graphical user interface, as shown and described. 